// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_
#define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_

#include <stdint.h>

#include <memory>
#include <string>

#include "base/callback.h"
#include "base/macros.h"
#include "content/browser/download/download_request_core.h"
#include "content/browser/loader/resource_handler.h"
#include "content/public/browser/download_interrupt_reasons.h"
#include "content/public/browser/download_manager.h"
#include "content/public/browser/download_save_info.h"
#include "content/public/browser/download_url_parameters.h"

namespace net {
class URLRequest;
} // namespace net

namespace content {
class ByteStreamReader;
struct DownloadCreateInfo;

// Forwards data to the download thread.
class CONTENT_EXPORT DownloadResourceHandler
    : public ResourceHandler,
      public DownloadRequestCore::Delegate,
      public base::SupportsWeakPtr<DownloadResourceHandler> {
public:
    struct DownloadTabInfo;

    // started_cb will be called exactly once on the UI thread.
    // |id| should be invalid if the id should be automatically assigned.
    DownloadResourceHandler(net::URLRequest* request);

    // static
    // This function is passed into ResourceDispatcherHostImpl during its
    // creation and is used to create instances of DownloadResourceHandler as
    // needed.
    // TODO(ananta)
    // Find a better way to achieve this. Ideally we want to move the logic of
    // creating DownloadResourceHandler instances out of
    // ResourceDispatcherHostImpl.
    static std::unique_ptr<ResourceHandler> Create(net::URLRequest* request);

    bool OnRequestRedirected(const net::RedirectInfo& redirect_info,
        ResourceResponse* response,
        bool* defer) override;

    // Send the download creation information to the download thread.
    bool OnResponseStarted(ResourceResponse* response, bool* defer) override;

    // Pass-through implementation.
    bool OnWillStart(const GURL& url, bool* defer) override;

    // Create a new buffer, which will be handed to the download thread for file
    // writing and deletion.
    bool OnWillRead(scoped_refptr<net::IOBuffer>* buf,
        int* buf_size,
        int min_size) override;

    bool OnReadCompleted(int bytes_read, bool* defer) override;

    void OnResponseCompleted(const net::URLRequestStatus& status,
        bool* defer) override;

    // N/A to this flavor of DownloadHandler.
    void OnDataDownloaded(int bytes_downloaded) override;

    void PauseRequest();
    void ResumeRequest();

    // May result in this object being deleted by its owner.
    void CancelRequest();

    std::string DebugString() const;

private:
    ~DownloadResourceHandler() override;

    // DownloadRequestCore::Delegate
    void OnStart(
        std::unique_ptr<DownloadCreateInfo> download_create_info,
        std::unique_ptr<ByteStreamReader> stream_reader,
        const DownloadUrlParameters::OnStartedCallback& callback) override;
    void OnReadyToRead() override;

    // Stores information about the download that must be acquired on the UI
    // thread before StartOnUIThread is called.
    // Created on IO thread, but only accessed on UI thread. |tab_info_| holds
    // the pointer until we pass it off to StartOnUIThread or DeleteSoon.
    // Marked as a std::unique_ptr<> to indicate ownership of the structure, but
    // deletion must occur on the IO thread.
    std::unique_ptr<DownloadTabInfo> tab_info_;

    DownloadRequestCore core_;
    DISALLOW_COPY_AND_ASSIGN(DownloadResourceHandler);
};

} // namespace content

#endif // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_
